The seedling in the pic, looks like my best out of 2 dozen seedlings that sprouted. It looked like yours, and finally died a couple seasons ago, it seems to be a soil problem, fatal leaf burn symptom and slow growth. My struggled for a few years or more, but enviably died, like the others which died within their first year of life.

My plant, was just a little taller then yours, but looked the same, looked better this time of year, but most of the leaves were dead by fall. One reason I finally decided to go with Myrica cerifera, for rootstock.

I was frustrated, I used a good potting soil, but some have said, that planting and native soils is better, it could be they don't like manufacture fake soils, or so much organic material.

I think the some of the Bay Area soils, maybe more viable for Myrica ruba seedlings.

That could be one factor. I have never successfully raised a yangmei seedling in a pot, even just for a few months. In comparison, I have never killed a single M. cerifera or M. californica, either in pot or in the ground.For all the yangmei seedlings in the ground, it makes a big difference whether it receives good shade.

I had a pleasant surprise last week: two yangmei seedlings in my seedbed! I bought 100 seeds from a Chinese Ebay vendor, and planted 50 on January 18, and 50 two weeks later after cold stratifying. There is so much disagreement about pre-treatment, that I scarified some of them (rubbing on concrete pavement ), treated some with GA, and cold stratified some. Some received two treatments, and others all three. I didn't keep track of which got which because I'm lazy. Whatever the case, 2% germination after a little over two months is better than what I got before.

Oh, before treating the seeds, I cut three open to see if they looked viable. Two were smaller, and were EMPTY inside (just a thick seed coat, no inner kernel). The third was larger and had what looked like a viable inner seed. I didn't want to cut any more open, so I can't say how many were actually duds, but this may explain why some people get low germination with this plant.

Seedling #3 just emerged! The other two are looking great so far; I keep them under my patio- they get mostly indirect sun and a few hours of direct afternoon sun. I occasionally acidify the irrigation water to 5.5 or so. If you're interested in the Chinese Ebay vendor, I can post it here.

This year I had a better graft take, on my largest and most growth flushed rootstock; last year it only kept one male graft, but this year, it kept two QiBi grafts and one of them is going crazy with growth. The next largest rootstock took one male graft low on the plant; and my potted rootstock again, did not even take one graft again.

I have concluded that they need to have a very good flush, for the grafts o take, and they need put on, here in the Central Valley, in March, if not mid Feb or so. The Myrica cerifera I have, seems to almost grow some all winter long, if not too cold, as it has been the last few years; but for the grafts to take, they need a supper good growth flush.

With this understanding, I can see why in China, why they maybe are soil planting the rootstock, for grafting.